Composite metal vessel



United States Patent O 3,503,598 COMPOSITE METAL VESSEL Louis Babel,Sanvigny-les-Bois, and Andr Girard, Nevers,

France, assignors to Societe Metallurgique dImphy, Paris, France, acompany of France Filed Nov. 8, 1967, Ser. No. 681,348 Claims priority,application France, Nov. 28, 1966,

Int. Cl. C21c 7,/00; H05b 5/02 U.S. Cl. 266--39 4 Claims ABSTRACT OF THEDISCLOSURE The invention relates to ya composite vessel, moreparticularly a ladle with a refractory cylindrical casing, intended tocontain molten metal and subjected to highintensity fields produced byan inductive circuit with very low andl low-frequency altern-atingcurrent.

These fields produce, along the parallel and meridian planes of thecasing, induced currents short-circuiting on themselves, causing heatingof the casing. This heating eiiect is reduced if the metal constitutingthe casing is nonmagnetic and the frequency is low.

With currents of very low frequency, for example 2 hz. or less, theliquid metal in the ladle can be stirred. However, since thenon-magnetic casing begins to melt before the frequency and intensity inthe field magnet are high enough, it is very difficult, if notimpossible, to produce in this metal an induced current of sufficientintensity to maintain the bath temperature, or-as is often desirable-toincrease this temperature to the value desired for casting, for exampleIduring and after degassing.

The object of the invention is to provide a non-magnetic, indeformablecasing which has high mechanical resistance, is refractory at hightemperatures, is fluid-tight in a vacuum or under pressure, and whichcan permit passage, without appreciable heating, of high-intensityfields from inductive currents of appropriate frequency.

According to the invention, the vessel is constituted, in the heatingzone, by assembling profiled metal elements made of a non-magnetic,refractory alloy, for example an austenitic steel, by means of tenonsand mortices on these elements, and these elements are electricallyinsulated from each other by an insulating, refractory seal constitutedby a heat-setting cement injected in a substantially liquid state intothe continuous interstices between the assembled metal elements.

According to another feature of the invention, a binder is providedaround the heating zone and comprises at least two layers of threads orbands, one layer consisting of threads or bands arranged along thegeneratrices of the cylindrical casing, and the other layer consistingof threads or bands wound helically around the first layer.

The invention will now 4be described with reference to an embodimentgiven by way of example and shown in the accompanying drawings.

FIGURE l is a general perspective view lof a vessel constituting apouring ladle, with parts cut away;

3,503,598 Patented Mar. 3l, 1970 ICC FIGURE 2 shows the bottom of thevessel;

FIGURE 3 is a perspective view of one of the elements constituting thecylindrical casing of the vessel, and

FIGURE 4 is a section on a line IV-IV in FIGURE 1, on a larger scale,showing an insulating seal between two elements in the casing.

The ladle shown in FIGURE 1 has a cylindrical casing or envelope 1extending over the entire heating height and assembled from profiledelements 1a. The upper end of the ladle has a cylindrical barrel-plate2, surmounted by a cover 3 with a pipe 4 and carrying trunnions 5 toallow pivoting.

The profiled elements 1a consist of panels such as that shown by way ofexample in FIGURE 3. This panel has two tenons 1b and two mortices 1cfor assembly with the identical adjacent panels.

The bottom 3 of the ladle (FIGURE 2) is made in the same manner byassembling fiat panels 3a.

The elements 1a, 3a are made of a non-magnetic, refractory alloy, suchas an austenitic steel, for example by moulding, within narrowtolerances. The dimensions of the tenons and mortices are such that whenthe elements are assembled according to the principle of theconstruction play, small interstices-for example of 1 to 2 mm.- can beleft between all the faces of mutual contact between vthe elements.These interstices are formed by means of appropriate packing strips ofrefractory insulating material, e.g. expanded polystyrene.

Before the elements are assembled, they are subjected to controlledoxidation which gives them preliminary insulation.

During assembly of the vessel, the packing strips are put in position atthe same time as the profiled elements.

When the casing for the vessel h-as been formed in this manner,refractory cement is injected under pressure until it fills theinterstices 1d between the elements 1a (FIG- URE 4). Suitably placedseals 1e prevent premature leakage.

The cement used is a refractory, heat-setting cement of low viscosity.In particular, it may be a slurry composed of a binder based on ethylsilicate, alcohol and refractories of a given grain size distribution,such as sillirnanites, zirconium oxides, etc.

At the ambient temperature a silica gel forms. This has p a dryingeffect and causes setting to begin. The whole is then grilled, thenheated to the final setting temperature of the order of 900 to impartthe final resistance to the insulating seals.

The operations mentioned produce a monolithic Vessel with permanentlyinterlocked profiled elements which have high lmechanical resistance andcan be subjected to high-intensity fields produced by inductive currentsof a sufficiently high frequency for the intended treatment of the metalbath.

To prevent the irregularities which might arise on account of thealternate heating and cooling, the vessel has-according to theinvention-a binder in the zone constituted by the assembled elements.

This binder is made with threads or bands, such as glass fibres withhigh mechanical properties or non-magnetic metal wires or bandsinsulated fromr each other.

These threads or bands are arranged in at least two layers. The firstlayer consists of threads or bands 6y arranged along the generatrices ofthe cylindrical casing 1. To this end hooks or similar means 7` (FIGUREl) are provided on the cylindrical barrel-plate 2 of the vessel, inorder to grip the threads or bands, which, under the end 3, are arrangedin layers of parallel threads or bands. The second layer consists ofthreads or `bands 8 wound helically around the first layer.

Each layer is coated with a lacquer or varnish, and finally the assemblyis placed in an oven before being taken into service.

What we claim is:

1. A composite Huid-tight refractory metal ladle for the treatment ofmolten metals comprising a cylindrical envelope surmounted by a cover, aheating zone formed by said envelope, a plurality of permanentlyinterlocked rectangular proled non-magnetic refractory metal alloyelements forming said heating zone, mortices and tenons on the sides ofeach of said elements locking adjacent ones of said elements togetherand means for electrically insulating said elements from each othercomprising an insulating refractory seal of a heat setting cement llingthe interstices between said interlocked elements.

2. A composite fluid-tight refractory metal ladle for the treatment ofmolten metals comprising a cylindrical envelope, a heating zone formedby said envelope, a plurality of interlocked rectangular profilednon-magnetic refractory metal alloy elements forming said heating zone,mortices and tenons on the sides of each of said elements lockingadjacent ones of said elements together and means for electricallyinsulating said elements from each other comprising an insulatingrefractory seal of a heat setting cement filling the interstices betweensaid CII interlocked elements including a binder around the heating zonecomprising at least two layers of'threads or bands for said binder, oneof said layers consisting of threads or bands arranged along thegeneratrices of the cylindrical casing, and the other of said layersconsisting of threads or bands wound helically around said ReferencesCited UNITED STATES PATENTS 2,170,254 8/1939 Seil 266-43 2,266,78512/1941 McLain 266-43 X 3,396,962. 8/19618 Smith et al 266-43 I. SPENCER.OVERHOLSER, Primary Examiner f JOHN E. ROETHEL, Assistant Examiner

